Color images are customarily obtained in the photographic art by reaction between an oxidation product of a silver halide developing agent and a dye-forming coupler. Pyrazolone couplers are useful for forming magenta dye images; however, such couplers have shortcomings with respect to color reproduction in that the unwanted absorption around 430 nm causes color turbidity. Bicyclic pyrazolo couplers, particularly pyrazolotriazole couplers, represent another class of couplers for this purpose. Examples of pyrazoloazole couplers are described in, for example, U.S. Pat. Nos. 4,443,536; 1,247,493; 1,252,418; and 1,398,979; and 4,665,015; 4,514,490; 4,621,046, 4,540,654; 4,590,153; 4,822,730 and European Patents 177, 765 and 119,860. One class of pyrazolotriazole couplers includes 1H-pyrazolo[3,2-c][1,2,4]triazole couplers and another includes 1H-pyrazolo[1,5-b][1,2,4]triazole couplers, such as described in European Patent 177765.
Pyrazoloazole couplers containing a t-butyl group at the 6-position are described in U.S. Pat. No. 4,882,266. and impart greater light stability to the resulting dyes. 1H-pyrazolo[1,5-b][1,2,4]triazole couplers with a fully substituted group in the 6-position and a phenyl substituent in the 2-position are described in EP 0571,959. U.S. Pat. No. 5,605,788 describes these types of couplers with aromatic sulfonamides on the 2-phenyl group. Similar couplers with aromatic and some aliphatic sulfonamides on the 2-phenyl ring are described in U.S. Pat. No. 6,232,055 and JP 08 146,575. While these sulfonamide substituted 2-phenyl substituted couplers have the advantage of light stability and hue, they are high melting solids and hard to disperse in common coupler solvents. In order for a coupler to be useful it must be soluble in the appropriate coupler solvents and not crystallize therefrom. When such crystallization occurs, loss in density and activity occurs and in the extreme case no dye is formed at all. Couplers with very high melting points of 140° C. or higher often show limited solubility in common coupler solvents. A problem to be solved is to provide couplers with the desirable sulfonamide substitution which have a reduced tendency to crystallize from the solvents they are dispersed in.